This invention relates generally to track type work machines, and more particularly to a drive sprocket for a track type work machine.
Work machines which utilize a track type drive mechanism have several advantages over wheel type work machines. The tracks give the work machine excellent traction while spreading the weight of the machine over a large area. Thus, the track type work machine has enhanced off road capabilities.
A typical undercarriage of a track type drive mechanism consists of a track made of a number of shoes linked together, a drive sprocket which drives the track, and a number of rollers which distribute the weight of the work machine along the track.
In a conventional track type drive, a tooth of the drive sprocket engages a stationary bushing in the shoe of the track. This type of engagement causes considerable wear as the teeth of the drive sprocket advance the track around the drive sprocket. A disadvantage to this type of track drive is that the bushings of the track must be replaced as they wear out. Replacing the shoes of the track and the teeth of the sprocket is costly and time consuming.
One method of reducing track wear is to mount a rotating bushing on the shoes of the track of the work machine. The rotating bushing eliminates much of the friction between the shoes and the teeth of the drive sprocket as the drive sprocket engages and disengages the track as the track is advanced around the drive sprocket. Mounting a rotating bushing on the shoe greatly reduces wear on the track. However, a disadvantage of mounting a rotating bushing on each shoe is the cost of the large number (typically 30 to 50) of bushings needed in order to place a bushing on each shoe of the track assembly.
Another method of reducing track wear is to mount rotating members on the drive sprocket. These rotating members engage drive lugs attached to each shoe of the track. This arrangement also reduces wear on the track. However, this approach also suffers from disadvantages. For example, one disadvantage this approach suffers from is the difficulty of replacing the rotating members on the drive sprocket as they wear out. In particular, replacing the rotating members on the drive sprocket can be costly and time consuming, which in turn increases the cost of operating the work machine.
The present invention is directed to overcoming one or more of the problems or disadvantages associated with the prior art.
In accordance with one embodiment of the present invention, there is provided a drive sprocket for a track type work machine. The drive sprocket includes a hub and a support secured to the hub. The drive sprocket also includes a cartridge assembly secured to the support. The cartridge assembly has (i) a bushing having a passageway defined therethrough, (ii) a pin having a longitudinal axis, the pin being located within the passageway so that a first end portion and a second end portion of the pin extend outwardly from the passageway of the bushing, (iii) a first collar having a first hole defined therein, the first collar being positioned relative to the pin so that the first end portion of the pin is disposed within the first hole, (iv) a second collar having a second hole defined therein, the second collar being positioned relative to the pin so that the second end portion of the pin is disposed within the second hole, (v) a first seal arrangement interposed the first collar and the bushing such that the first seal arrangement contacts the first collar and the bushing, and (vi) a second seal arrangement interposed the second collar and the bushing such that the second seal arrangement contacts the second collar and the bushing. The first collar is fixed in relation to the pin so that the first collar is unable to rotate relative to the pin. The second collar is fixed in relation to the pin so that the second collar is unable to rotate relative to the pin. The bushing is able to rotate relative to the pin around the longitudinal axis.
In accordance with another embodiment of the present invention, there is provided a track type work machine. The track type work machine includes a track shoe and a drive lug secured to the track shoe. The work machine also includes a drive sprocket having (i) hub, (ii) a support secured to the hub, and (iii) a cartridge assembly secured to the support, the drive sprocket being positioned relative to the drive lug such that the cartridge assembly is in contact with the drive lug. The cartridge assembly includes (i) a bushing having a passageway defined therethrough, (ii) a pin having a longitudinal axis, the pin being located within the passageway so that a first end portion and a second end portion of the pin extend outwardly from the passageway of the bushing, (iii) a first collar having a first hole defined therein, the first collar being positioned relative to the pin so that the first end portion of the pin is disposed within the first hole, (iv) a second collar having a second hole defined therein, the second collar being positioned relative to the pin so that the second end portion of the pin is disposed within the second hole, (v) a first seal arrangement interposed the first collar and the bushing such that the first seal arrangement contacts the first collar and the bushing, and (vi) a second seal arrangement interposed the second collar and the bushing such that the second seal arrangement contacts the second collar and the bushing. The first collar is fixed in relation to the pin so that the first collar is unable to rotate relative to the pin. The second collar is fixed in relation to the pin so that the second collar is unable to rotate relative to the pin. The bushing is able to rotate relative to the pin around the longitudinal axis.
In accordance with still another embodiment of the present invention, there is provided a method of servicing a drive sprocket having (i) a hub and (ii) a support secured to the hub. The method includes securing a cartridge assembly to the support. The cartridge assembly has (i) a bushing having a passageway defined therethrough, (ii) a pin having a longitudinal axis, the pin being located within the passageway so that a first end portion and a second end portion of the pin extend outwardly from the passageway of the bushing, (iii) a first collar having a first hole defined therein, the first collar being positioned relative to the pin so that the first end portion of the pin is disposed within the first hole, (iv) a second collar having a second hole defined therein, the second collar being positioned relative to the pin so that the second end portion of the pin is disposed within the second hole, (v) a first seal arrangement interposed the first collar and the bushing such that the first seal arrangement contacts the first collar and the bushing, and (vi) a second seal arrangement interposed the second collar and the bushing such that the second seal arrangement contacts the second collar and the bushing. The first collar is fixed in relation to the pin so that the first collar is unable to rotate relative to the pin. The second collar is fixed in relation to the pin so that the second collar is unable to rotate relative to the pin. The bushing is able to rotate relative to the pin around the longitudinal axis. The bushing, the pin, the first collar, the first seal arrangement, the second collar, and the second seal arrangement define a substantially sealed chamber between an interior surface of the bushing and an exterior surface of the pin.
In accordance with yet another embodiment of the present invention, there is provided a drive sprocket arrangement having (i) a hub and (ii) a support secured to the hub. The support has a first aperture and a second aperture defined therein. The arrangement includes a cartridge assembly configured to be press fit into the first aperture and the second aperture. The cartridge assembly has a bushing having a passageway defined therethrough and a pin having a longitudinal axis. The pin is located within the passageway so that a first end portion and a second end portion of the pin extend outwardly from the passageway of the bushing. The arrangement also includes a first collar having a first hole defined therein. The first collar is positioned relative to the pin so that the first end portion of the pin is disposed within the first hole. The arrangement also includes a second collar having a second hole defined therein. The second collar is positioned relative to the pin so that the second end portion of the pin is disposed within the second hole. The arrangement further includes a first seal arrangement interposed the first collar and the bushing such that the first seal arrangement contacts the first collar and the bushing. The arrangement also includes a second seal arrangement interposed the second collar and the bushing such that the second seal arrangement contacts the second collar and the bushing. The first collar is fixed in relation to the pin so that the first collar is unable to rotate relative to the pin. The second collar is fixed in relation to the pin so that the second collar is unable to rotate relative to the pin. The bushing is able to rotate relative to the pin around the longitudinal axis.